This application incorporates by reference Taiwanese application Serial No. 089222406, Filed Dec. 22, 2000.
1. Field of the Invention
The invention relates in general to an Automatic Document Feeder (ADF), and more particularly to an ADF using a supporting structure for feeding documents smoothly.
2. Description of the Related Art
Feeding documents smoothly is important for every machine equipped with an ADF (Automatic Document Feeder), such as scanners, printers, facsimile machines or the like. The scanner with an ADF can carry a large amount of documents ready for use at a time, which is more efficient than the flatbed scanner does. Compared with the traditional machine, which is restricted by the image processing speed and memory capacity, the machine nowadays, requires more documents at a time for an efficient and timesaving operation, especially for office automation. However, there are restrictions of the traditional feeding device under some circumstances. For example, the document to be fed might not contact with the feed roller for being carried when the space of the input tray is large but there are only a little documents put in the input tray. The supporting structure is therefore developed for being fixed on the input tray.
Referring to FIG. 1A, a cross-sectional view of a conventional ADF is illustrated. As shown in FIG. 1A, the ADF 100 may be applied in scanners, printers, facsimile machines or the like for feeding the document 102 to the machines. The ADF 100 includes an input tray 104, a feed roller 106, a feed pad 110, a flat board 108 and a spring 111. The input tray 104 is for receiving a document 102. One end of the flat board 108 is pivoted on the input tray 104 by a hinge 115. Besides, one end of the spring 111 is fixed on the flat board 108 while the other end of the spring 111 is fixed on the notch 113 of the input tray 104. The flat board 108 and the input tray 104 therefore form an angle xcex81. The rim of the feed roller 106 touches the feed pad 110. The feed roller 106 and the feed pad 110 therefore create a feeding end 112. When the feed roller 106 rotates around the axis 116, the feed roller 106 drives the document 102 to advance by fiction. The more documents the flat board 108 carries, the smaller the angle xcex81 is. The flat board 108 supports the document 102 by the elasticity of the spring 111. The leading edge of the document 102 gets into the feeding end 112 so that the feed roller 106 can drive the document 102 to advance while rotating.
Referring to FIG. 1B, a cross-sectional view of the ADF in FIG. 1A which carries a stack of documents is shown. As shown in FIG. 1B, documents 114 are placed on the input tray 104. The documents 114 include a document 102a, document 102b, documents 114a and document 102c. The documents 114 in FIG. 1B are a stack of paper and the document 102 in FIG. 1A is a sheet. The documents 114 are therefore heavier than the document 102. Besides, the gravity of the stack of paper 114 downward is far larger than the elasticity of the elastic film 108 upward. The angle xcex82 between the flat board 108 and the input tray 104 is less than xcex81. The leading edge of the document 102a gets into the feeding end 112.
When the feed roller 106 starts to rotate around the axis 116, the feed roller 106 drives the document 102a to advance toward the feeding end 112. After the document 102a completely passes through the feeding end 112, the elasticity from the spring 111 pushes the document 102b upward for getting into the feeding end 112. The document 102b is then driven to pass through the feeding end 112 by the feed roller 106. The same operation will be proceeded and the amount of the documents 114 therefore gradually decreases, meanwhile, the angle xcex82 between the flat board 108 and the input tray 104 becomes larger. The feed roller 106 drives the rest of documents put on the input tray 104 to advance toward the feed end 112 sequentially.
After the feed roller 106 drives the document 102a, document 102b and documents 114a to sequentially pass through the feeding end 112 and to be completely fed into the machine (not shown). The last document 102c is left on the input tray 104 and the angle xcex82 between the flat board 108 and the input tray 104 becomes equal to xcex81 due to the upward elasticity of the spring 111. The leading edge of document 102c gets into the feeding end 112 for being fed 102 and the feeding process of the ADF 100 is therefore finished.
Nevertheless, the ADF 100 stated above with a pivotal flat board, hinge and spring is structurally complex, costly and difficult to assemble during manufacturing.
It is therefore an object of the invention to provide an Automatic Document Feeder with an elastic film for supporting the documents put on the input tray, the documents are able to be carried by the feed roller for being fed smoothly and sequentially.
The invention achieves the above-identified objects by providing an ADF, which includes an input tray and elastic film. The input tray is for receiving a document or documents to be fed and the elastic film disposed upon the input tray is for supporting the document or documents to be fed by bounce. The elastic film includes a jointing portion for fixing the elastic film onto the input tray and a supporting portion forming an angle with the input tray for supporting the document or documents to be fed. The elastic film further includes a bending portion, wherein one end of the bending portion connects to the supporting portion and the other end of bending portion bends towards the input tray.